<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <button class="btn">停止</button>
  <script>
    var oBtn = document.querySelector(".btn");
    oBtn.onclick = function(){
      // clearTimeout(t);
      clearInterval(t);
    }
    // var t = setTimeout(function(){
    //   console.log("hello 倒计时")
    // },5000);
    // var t = setInterval(function(){
    //   console.log("hello 循环")
    // },1000)
  </script>
</body>
</html>